So for my own edification, let me see if I understand what happened here: Insulated neutral bus was at 120V. Both lugs on the same leg at 120V. All the 240 volt loads would've been supplied with 120, all the 120 volt loads would've been seeing 240.
I can't tell what's going on with any of the grounds or the GEC, but I assume something was grounded somewhere, and when DIY reinstalled the bonding jumper he saw a dead short on the unfused line conductors. The neutral lugs in the meterbase look insulated, but from the size of the scortch-mark, maybe not?
-John
